What principle does the operation of a pressure regulating valve rely on?

The operation of a pressure regulating valve relies on pressure differences to function effectively. These valves are designed to maintain a specific downstream pressure regardless of fluctuations in upstream pressure. When there is a difference in pressure between the inlet and the outlet of the valve, the valve responds to this differential by adjusting its position.

When the downstream pressure drops below the set point, the valve opens to allow more flow through and increase the pressure. Conversely, if the downstream pressure exceeds the desired level, the valve closes to restrict flow and lower the pressure. This mechanism ensures a consistent and stable pressure downstream, which is crucial for the optimal operation of various HVAC systems.

Other concepts like thermodynamic cycles, liquid expansion, and gas compression, while relevant in various contexts within HVAC systems, do not pertain directly to the primary function of a pressure regulating valve. Those processes serve different purposes, such as refrigerant flow management or thermal management, which are not the focus of how pressure regulating valves operate.